At a glance
Also known as
Pregnancy test; qualitative hCG; quantitative hCG; beta hCG
Why get tested?
Testing for human chorionic gonadotropin levels is done to diagnose and monitor:
- trophoblastic disease (tumours developing from the placenta during pregnancy)
- tumours (tumours developing in the testes of males from a sperm cell or in the ovaries of females from an egg cell)
When to get tested?
If you think you may be pregnant, a blood test for hCG may be positive as early as one week after conception, while a urine test, such as the tests you can do at home, may be positive at around the time of the first missed menstrual period.
A doctor may wish to check your hCG level if you have fallen pregnant but you are having problems with the pregnancy, such as symptoms or signs of an or miscarriage. The doctor may also check hCG levels if he or she thinks your symptoms suggest trophoblastic disease or a germ cell tumour.
A urine sample collected first thing in the morning or a blood sample drawn from a vein in the arm
Test preparation needed?
None needed, however do not drink large amounts of fluid before collecting a urine sample for pregnancy testing as very dilute urine may result in a test result.
What is being tested?
hCG is a hormone produced in the placenta of a pregnant woman. A pregnancy test is a specific blood or urine test that can detect hCG and confirm pregnancy. This can be detected by a blood test as early as one week after conception or by a urine test at around the time of the first missed menstrual period.
hCG production doubles about every 48 hours for the first month of a pregnancy and continues to rise steadily, until about 10-12 weeks when levels drop until about the 20 week mark, and then continue largely the same until term.
It is important to note that there is a wide range of hCG levels between individuals, but this trend appears to be relatively constant. Estimates of gestational age are difficult to do using hCG due to this wide variation between individuals, so ultrasound investigations are used to check pregnancy duration. hCG is no longer detectable a few weeks afer delivery.
During the early weeks of pregnancy, hCG is important in maintaining function of the (the mass of cells that forms from a mature egg into the developing embryo).
If something goes wrong with the pregnancy, the level of hCG may be higher or lower than usual. In the case of an ectopic pregnancy, the hCG may be lower than usual and, if a woman miscarries, the level of hCG will fall quickly. If a woman develops trophoblastic disease, the hCG level may be higher than expected.
hCG is also produced by some tumours.
Repeat testing will help to monitor the hCG levels where necessary in these situations.
How is the sample collected for testing?
When a test for hCG is done to see if a woman is pregnant, it may be done as a urine test or as a blood test from blood drawn from a vein in the arm. The urine test should be done on a urine sample collected first thing in the morning, as this is the time when urine is most concentrated.
When a test for hCG is done on a pregnant woman to help diagnose problems with the pregnancy, it should be done as a blood test, and if it needs repeating 48 hours later, this preferably should be done at the same laboratory.
When a test for hCG is done on a male or female to test for a germ cell tumour, it should be done as a blood test.